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help > RE: How to use "age" as covariates?
Jun 20, 2016 04:06 PM | Alfonso Nieto-Castanon - Boston University
RE: How to use "age" as covariates?
Hi Chaleece,
That contrast is interesting but not exactly what you are aiming for (precisely that would give you those areas where the connectivity in the control group is larger than the connectivity changes associated with severity in the patients group). I would propose to use instead a contrast of [0 0 1] (two-sided) first to identify those areas where there are significant differences in connectivity associated with severity within the patients group, and then, within any significant cluster, use "extract values" to look at the sign of the [-1 1 0] contrast and the sign of the [0 0 1] contrast (the first contrast quantifies the difference in connectivity between controls and the 0-severity level in patients, while the second contrast quantifies the changes in connectivity associated with increased severity; those clusters where the signs of those two contrasts are the same will identify the subset of regions that show increases in patient vs. control differences in connectivity with increasing severity)
Hope this helps
Alfonso
Originally posted by Chaleece Sandberg:
That contrast is interesting but not exactly what you are aiming for (precisely that would give you those areas where the connectivity in the control group is larger than the connectivity changes associated with severity in the patients group). I would propose to use instead a contrast of [0 0 1] (two-sided) first to identify those areas where there are significant differences in connectivity associated with severity within the patients group, and then, within any significant cluster, use "extract values" to look at the sign of the [-1 1 0] contrast and the sign of the [0 0 1] contrast (the first contrast quantifies the difference in connectivity between controls and the 0-severity level in patients, while the second contrast quantifies the changes in connectivity associated with increased severity; those clusters where the signs of those two contrasts are the same will identify the subset of regions that show increases in patient vs. control differences in connectivity with increasing severity)
Hope this helps
Alfonso
Originally posted by Chaleece Sandberg:
Hi CONN-ers!
I have a similar question, but want to make sure I'm not over-generalizing to my data.
I have a group comparison between patients and controls and I'd like to see the effect of variables that are not present in the control group (e.g., lesion size and severity). I have set up the contrast as [1 0 -1] for 'control' 'patient' and 'lesion size'. Am I way off? I am hoping to be able to say something like: As lesion size increases, the difference in connectivity between groups increases for these connections. I've looked at the calculator for one of the connections, and this seems to be the case. I just want to make sure the way I've set up the contrast is legit.
Thanks!
Chaleece
I have a similar question, but want to make sure I'm not over-generalizing to my data.
I have a group comparison between patients and controls and I'd like to see the effect of variables that are not present in the control group (e.g., lesion size and severity). I have set up the contrast as [1 0 -1] for 'control' 'patient' and 'lesion size'. Am I way off? I am hoping to be able to say something like: As lesion size increases, the difference in connectivity between groups increases for these connections. I've looked at the calculator for one of the connections, and this seems to be the case. I just want to make sure the way I've set up the contrast is legit.
Thanks!
Chaleece